1. Field of the Invention
The present invention relates to poly(iminomethylene)polymers, particularly copolymers thereof. This invention also relates to vinyl isocyanide compounds for the preparation thereof.
2. Description of the Prior Art
The homopolymerization of isocyanides, RNC, yields a rather unusual class of polymers, namely the poly(iminomethylenes), having the formula ##STR2## These polymers are of interest as their viscosity behavior, Debye-Scherrer X-ray composites, and optical rotation data suggest that the polymers have a rigid rod helical structure. The same structure appears to be consistent with observations from molecular models. F. Millich, Adv. Polym. Sci., 19, 117 (1975) and Chem. Rev., 72, 101 (1972). With the recognition that a helical structure is the most likely structure, subsequent experimentation soon indicated that various isocyanide oligomers could be resolved into fractions having (+) and (-) signs of optical rotation. R. J. M. Nolte et al, J. Am. Chem. Soc. 96, 5932 (1974). Hence, the poly(iminomethylenes) appear to have a chiral helical rigid rod structure.
The chirality of these polymers renders them of interest and useful as chiral supports for asymmetrical catalysts. Moreover, these polymers have a backbone of carbon atoms each having a nitrogen atom bonded directly thereto by means of a double bond which renders them of interest as building blocks for novel conducting polymeric materials.
The first characterized high polymer of an isocyanide, RNC, and a catalytic synthetic procedure were reported in 1965. However, although some polyisocyanide studies have been conducted, as described above, more extensive investigations of the synthesis and properties of these polymers have been hampered by the extreme insolubility of most of the poly(iminomethylenes). Moreover, the polymer insolubilities have largely prevented investigations pertaining to the possible uses for these polymers. With the combination of chirality and rigidity, the poly(iminomethylenes) should offer a wide range of uses such as selective supports in chromatography, as enantioselective catalysts, and as specific reagents with respect to substrates of biochemical importance. Unfortunately, the realization of these possiblities has been frustrated due to the pervasive insolubility of the poly(iminomethylenes).
For example, among the poly(iminomethylenes) derived from simple isocyanides, those prepared from phenethyl and tert-butyl isocyanides have been found to be soluble in chloroform, whereas those prepared from methyl, ethyl, n-butyl, isopropyl, cyclohexyl and phenyl isocyanides are insoluble in chloroform. Rec. Trav. Chim. Pays-Bas., 1973, 92, 83, R. J. M. Nolte et al. Similarly, among the polymers obtained from the homopolymerization of vinyl isocyanides, those prepared from (CH.sub.3).sub.3 CCH.dbd.CHNC, C.sub.6 H.sub.5 CH.dbd.CHNC and C.sub.6 H.sub.5 C(CH.sub.3).dbd.CHNC are soluble in chloroform, whereas those prepared from CH.sub.3 CH.dbd.CHNC, (CH.sub.3).sub.2 C.dbd.CHNC, 2,4,6-(CH.sub.3).sub.3 C.sub.6 H.sub.2 CH.dbd.CHNC, and CH.sub.3 CH.dbd.C(CH.sub.3)CH.dbd.CHNC are insoluble in chloroform.
Thus, the limited number of isocyanides that polymerize to soluble poly(iminoethylenes) severely limits the range of pendant groups that can be attached to a soluble poly(iminomethylene) backbone through the homopolymerization of isocyanides.
Hence, a need continues to exist for a poly(iminomethylene) type polymer which is soluble and which would, therefore, facilitate the study and use of these polymers.